Apple - Mite Problem?

This dwarf rootstock James Grieve was bought in April this year. It is fruiting well despite the inclement weather in Belfast. But, over the past few weeks the leaves started to curl and go brown with a few dropping. The underside shows red patches (not the raindrops!) which contain what appear to be red spider mites or eggs. I'm not sure.

I'd be grateful for advice. If it is in fact a mite infestation, I believe there are predatory mites etc which can be used for control. But where to get these?

Incidentally, I have a standard James Grieve in the garden which is also affected although less severely.